Selco Genesis 240 TLH, Руководство по ремонту

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Warnings, precautions, general information - Diagnostics and repair instruments and tools 121
8) WARNINGS, PRECAUTIONS, GENERAL
INFORMATION ON EXECUTING REPAIRS.
Repairs may be executed by qualified personnel only.
Before attempting any repairs, we advise you to read and
understand the information in this manual, especially in regard
to safety recommendations.
Do not carry out any repair unless another person is present
who can provide help in case of an accident.
To repair equipment, access is necessary to the internal parts of the
machine, and to obtain this, some protective panels have to be
removed. Therefore, some extra precautions are necessary, over
and above those applying to normal use of the machine for
welding, in order to prevent any damaged caused by contact with:
- Live parts
- moving parts
- parts at high temperature
- Live parts:
IMPORTANT!: When accessing parts inside the
machine, remember that turning off the switch will
not prevent the danger of electric shocks. We the-
refore advise you to remove the plug and wait for
about a minute before attempting any job.
Further, as capacitors charged with high voltage may be pre-
sent, wait about a minute before working on the internal parts.
IMPORTANT!: When taking measurements,
remember that the measuring instruments them-
selves can become live and, therefore, do not touch
their metal parts.
IMPORTANT!: In version TLH, when the TIG mode
is selected, the machine generates a series of high
voltage pulses (approximately 10.000 V) to spark the
welding arc. When an arc sparking test in TIG with
H.F. discharge is not expressly included in the diagnostic pro-
cedure, you are advised to disconnect the connector CN2
from board 15.14.192.
- Moving parts:
IMPORTANT!: Keep your hands well away from the
fan when the machine is connected to the power
supply. Make sure that the power plug is removed
and that the fan is idle before replacing it.
- Parts at high temperature:
IMPORTANT!: When you have to handle internal
parts of the machine, remember that some could
be at high temperature. In particular, do not touch
cooling radiators.
9) DIAGNOSTICS AND REPAIR INSTRUMENTS
AND TOOLS.
9.1)
Diagnostics instruments and tools
9.1.1)
Level 1
You will need the following:
- a multimeter with the following scales:
Ohm : from 0 to a few Mohm
Diode test
Direct voltages (Vdc): from mVdc to 1000 Vdc
Alternate voltages (Vac): from 10 Vac to 700 Vac
NOTE : We recommend you to use an instrument with an
automatic scale, because, if the machine faulty, in theory, the
level of the electrical value to be measured cannot be foreseen.
- a shunt of 240 A @ 60 mV .
NOTE : Remember that other values may be equally suitable,
but you will sacrifice accuracy at larger capacities, whereas on
low capacities, rapid measuring is necessary to prevent the
shunt overheating.
9.1.2)
Level 2
In addition to the instruments and tools recommended at the
previous point, you will also need the following:
- an oscilloscope with the following characteristics :
- two channels
- 100MHz of passband
- time base up to 200ms, and ROLL option for the
trigger
- a probe with the following characteristics :
- attenuation of 10:1
- insulating voltage to ground of at least 600Vrms.
- a probe with the following characteristics :
- attenuation of 100 : 1
- insulating voltage to ground of at least 1000Vrms .
IMPORTANT !: Any connection to the ground, whe-
ther direct or through the metal frame of the oscil-
loscope must be eliminated. However, we advise
you to make a ground connection for the oscillo-
scope through an in-series capacitor-resistor cir-
cuit, where C = 10 nF 1600 V, R = 220Kohm 1W.